Axle suspension for automotive vehicles

ABSTRACT

In automotive vehicles, in order to ensure that the engine stub shaft and the differential stub shaft (both connected with the drive shaft by universal joints) form identical angles with the drive shaft at all times during springing motions of the driven axle, the latter is mounted on the vehicle chassis by means of a quadrilateral suspension. One side of said suspension is a vertically pivotable axle bracket made of a horizontally flexing leaf spring that carries the axle tube and an air spring engaging said chassis; an opposite side of said suspension is a vertically flexing leaf spring held at its ends and attached at its mid portion to said axle tube.

[ 51 May 23, 1972 United States Patent Schaeff [54] AXLE SUSPENSION FORAUTOMOTIVE .267/18 X .....267/18 X ....267/31 X 3,237,957 3/1966 HarbersVEHICLES 3,309,107 3/1967 Chieger... Am Hollberg Bensheim-Auerbach,Germany Dec.4, 1969 19, 3,547,21512/1970 Bird.....................

[72] Inventor: h'iedrich Schaefl,

22 Filed:

Primary Examiner-A. Harry Levy Attorney-Edwin E. Greigg [21] Appl.N0.:882,159

ABSTRACT In automotive vehicles, in order to ensure that the engine stubshaft and the differential stub shaft (both connected with the driveshaft by universal joints) form identical an drive shaft at all timesduring springing motions axle, the latter is mounted on the vehiclechassis by means of a quadrilateral suspension. One side of said suscally pivotable axle bracket made of a horizontally flexin spring thatcarries the axle tube and an air spring en chassis; an opposite side ofsaid suspension is a vertically flexing leaf spring held at its ends andattached at its mid to said axle tube.

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UNITED STATES PATENTS 1,679,268Rigney.....................................267/31 SCIaiIIB,loDravvingFigures PATENTEDMAY 23 I972 SHEET 2 [IF 5 PATENTED MAY 2 3I972 SHYU l UF 5 K a mm PATENTEDHMZS 1972 3 664,452

' sum 5 OF 5 BRACKGROUND OF THE INVENTION This invention relates to asuspension for a vehicle axle driven by a drive shaft and connected witha differential .and is further of the type that is associated with aswinging axle bracket, one end of which is pivotally held by thechassis, while the other end is secured to the chassis with theinterposition of an air spring. To the axle bracket there is fixedlysecured the axle housing or axle tube.

It is a disadvantage of known axle structures that the stub shaftsconnected to both ends of the drive shaft by means of universal jointsand associated with the engine and with the differential, respectively,are disposed parallel with one another only in a normal position (travelon plane, smooth surface). During springing, however, the said stubshafts form unequal angles with the drive shaft axis. The consequence isa non-uniform rotational speed of the stub shaft that drives thedifferential resulting in an uneven run of the vehicle.

In order to maintain the angle deviations of the universal joints of thedrive shaft at a small value, suspension structures for driven vehicleaxles have been provided, wherein the axle is mounted on a forwardlyprojecting auxiliary frame joined to the middle of the vehicle frame atthe frontal portion thereof. The air springs are carried by that portionof said auxiliary frame that extends rearwardly beyond the axle. Thelatter is held in axial direction by means of a transversal member. Sucha structure involves considerable expense and may not be used forconverting existing vehicle structures.

OBJECT, SUMMARY AND ADVANTAGES OF THE INVENTION It is an object of theinvention to provide an improved suspension for a driven vehicle axle toensure, in a simple and relatively inexpensive manner, that the stubshafts connected to the drive shaft by universal joints are disposedparallel with one another at all times resulting in an identical anduniform rotational speed thereof.

Briefly stated, according to the invention there is provided,

for each end of the axle, a quadrilateral axle suspension, one sideof-which is formed by a first leaf spring which flexes vertically,parallel with the springing direction of said air spring. That side ofsaid quadrilateral axle suspension which lies opposite said first leafspring constitutes said axle bracket and is formed as a second leafspring that flexes horizontally in a directionparallel with the axle.

The spring leaf or spring leaves of the first leaf spring ofeachquadrangular suspension are soft and serve to take up axial forcesgenerated between the axle and the chassis. The first leaf springsbecome effective when the air springs are active. In case of non-uniformspringing, the two first leaf springs are flexed and twisted. The secondleaf springs, on the other hand, pivot during each springing motion andare twisted in case ofuneven springing of said air springs.

The aforenoted structure may be installed in existing vehicles toreplace conventional suspension structures. Such installation does notrequire any substantial modification of the vehicle chassis, sincecomponents thereof may be incorporated in the suspension according tothe invention.

The invention will be better understood, as well as further objects andadvantages will become more apparent, from the ensuing detailedspecification of several exemplary embodiments takenin conjunction withthe drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a composite front elevationalview (to the right of the center line) and rear elevational view (to theleft of the center line) of a first embodiment of the invention;

FIG. 2 is a sectional view along line A-A of FIG. 1;

FIG. 3 is a sectional view along line B-B of FIG. 2;

FIG. 4 is a sectional view along line C-C of FIG. 2;

FIG. 5 is a sectional view along line DD' of FIG. 4;

FIG. 6 is a side elevational view of a second embodiment of theinvention;

FIG. 7 is a diagrammatic view of a drive shaft and adjacent associatedcomponents;

FIG. 8a is a partial rear elevational view of a third embodiment of theinvention;

FIG. 8b-is a sectional view taken along line E--E of FIG. 8a; and

FIG. 8c is a partial side elevational view of the structure shown inFIG. 8a.

DESCRIPTION OF THE EMBODIMENTS In FIG. 1 there is shown-a chassis 1,wheels 2, an axle tube 3, a differential housing 4, a differential stubshaft 5, air springs 6, anair spring support beam 7, and a clamping yoke8 affixed to the axle tube 3.

Turning now to FIG. 2, a first leaf spring 9 formed of two superposedindividual springs extends in the direction of vehicle travel and isfixedly held at its mid portion by the clamping yoke 8. The rear springterminal 11 is suspended from a link 10 which is coupled to a springsupport 12. The latter, in turn, is afiixed to the chassis 1. The otherterminal 13 of the first leaf spring 9 is provided with a joint which isreceived in a fork or eyelet 14 of a linkage bracket 20. The latter isprovided with three further coupling eyeletslS, 16 and 17. The bracket20 is rigidly affixed to the chassis 1 by eyelet 15 coupled to support18 and by eyelet 16 connected to support 19. Supports 18 and 19 areaffixed to chassis I. It is to be noted that supports 12 and 18 in aconventional suspension structure prior to conversion may have served assuspensions for a leaf spring stack.

The eyelet 17 of the linkage bracket 20 forms a joint for a supportmember 21 which holds one end 22 of a second leaf spring 23 which,similarly to the first leaf spring 9, is also formed of two springleaves. A further support member 24 holds the other end 25 of the secondleaf spring 23 and is rigidly connected withthe air spring support beam7. With the second leaf spring 23 there is associated a third springsupport membe'r-26which connects the mid portion of the second leafspring 23 with the clamping yoke 8 of the axle tube 3 by means of ajoint 27. As it may be observed from FIGS. 1 and 2, the leaf spring 23is so dimensioned that it is relatively wide in a first plane thatextendssubstantially vertically and longitudinally relative to thedirection the vehicle travels and itis relatively narrow in a secondplane normal to the first plane.

The afore-described structure is duplicated adjacent the other end ofthe axle on theother side of the vehicle.

When the vehicle is in motion on a plane surface, the first leaf spring9 and the second leaf spring 23 remain unflexed. Said first leaf spring9 and second leaf spring 23 form two opposite sides of a quadrilateralsuspension, the third and the fourth sides of which are formed bytheclamping yoke 8 and the linkage bracket 20, respectively.

If the air'spring 6 is compressed; the first leaf spring 9 is flexedupwardly by the clamping yoke' 8. It is noted that the first leaf spring9 also replaces the transversal stabilizer required in conventional axlesuspension structures, since said first leaf spring 9 is capable ofrigidly taking up axial forces because of its arrangement parallel withthe direction of travel and transmitting them to the chassis 1. During aflexing of the an identical extent which is a desired feature of thestructure according to the invention.

During springing motion of air springs 6, the second leaf spring or axlebracket 23 pivots in the eyelet 17. If said springing motion is uneven,the air bags 6 are sprung unevenly, the air spring support beam 7 willassume a position inclined with respect to the path of travel, and thusboth the second leaf springs 23 will be twisted by the torque generated.

It is thus seen that in this manner the first leaf spring 9 compels thedifferential housing 4 to maintain its orientation for all springingmotions. In FIG. 7 there is shown the differential housing 4 with thedifferential stub shaft 5 and the drive shaft 30 with the universaljoints 31 and 32, as well as the engine" stub shaft 33. Due to thekinematics of the quadrilateral suspension 8, 9, 23, 20, the angle awhich is formed between the engine stub shaft 33 and the drive shaft 30,as well as the angle [3 which is formed between the differential stubshaft and the drive shaft 30, remains ractically unchanged when thedistance between the differential housing 4 and the chassis 1 changes.

FIGS. 3 and 4 show that the terminals 22 and 25 of the second leafspring 23 are secured in the supports 21 and 24, respectively, by meansof shackles 28 tightened by counterscrews. The cross sectional FIGS. 3,4 further illustrate that the leaf spring 23 is formed of two parallelspaced spring leaves.

As seen in FIG. 5, the air spring support beam 7 is hollow and isdownwardly open by means of a longitudinal slot 29. The beam structureis thus adapted to deform responding to a torque, while it remainssubstantially rigid to a bending force.

Turning now to FIG. 6, the embodiment shown therein differs from theembodiment hereinabove described in that there is provided an inflatableair bag 34 disposed on an extension 35 of the second leaf spring 23remote from the air spring 6. The air bag 34, which is affixed to theextension 35 by means of a support 36, is in operative engagement withthe linkage bracket 20. The purpose of the air bag 34 is describedhereinafter.

It is sometimes a requirement for example, for some types of loading orunloading operations to lower the vehicle chassis 1 with respect to theaxle tube 3 to a greatest possible extent. For this purpose the airsprings 6 are vented. Even though the first leaf spring 9 is relativelyweak, the weight of the chassis 1 may not be sufficient to overcomeentirely the upwardly directed opposing spring force and, consequently,the chasis will not sink low enough. For assisting the gravitationalforce of chassis l, the air bag 34 is inflated. The force thus generatedimparts a counterclockwise torque on the second leaf spring 23 aboutjoint 17. As a result, the downward movement of chassis 1 ispower-assisted; the first leaf spring 9 is flexed upwardly.

Turning now to FIG. 8a, the air spring support beam is formed here as asolid bar 47 of rectangular cross section extending edgewise under thechassis 1 and carrying the air springs 6. As best seen in FIG. 8b, eachair spring 6 is affixed to the bar 47 by means of a support 40 andshackles 41. The support 40 is welded to the base of the air spring 6.The relatively flat bar 47, similarly to the beam 7, is adapted to twistwhen exposed to a torque.

In FIG. 8c there is illustrated the support 24 which carries the leafspring 23 and which is secured to the bar 47 by means of bolts andstraps 42.

In case of uneven springing motions of air springs 6 (particularly incurves), the bar 47 is twisted, but not bent. For such instances the bar47 functions as a stabilizer and delays the normal flexing.

That which is claimed is:

1. In an axle suspension for automotive vehicles of the type including(a) a vehicle chassis, (b) a differential associated with the axle, (c)a drive shaft for driving said axle, (d) an axle bracket pivotallyconnected to the vehicle chassis, (e) a horizontal axle tube affixed tosaid axle bracket and extending substantially normal to the direction oftravel and (f) air spring means supported at least indirectly by saidaxle bracket and connected to said chassis, the improvement comprising aquadrilateral suspension having A. a leaf spring constituting said axlebracket and forming a first side of said quadrilateral suspension, saidleaf spring being relatively wide in a first plane extendingsubstantially vertically and longitudinally relative to the direction oftravel, said leaf spring being relatively narrow in a second planenormal to said first plane, said leaf spring being adapted to flex in adirection parallel with said axle tube, B. a clamping yoke forming asecond side of said quadrilateral suspension and situated adjacent saidleaf spring,

said clampingyoke carrying said axle tube and C. means for jomtedlysecuring said clamping yoke to said leaf spring,

D. means forming a third side of said quadrilateral suspension, saidthird side being disposed opposite said first side, and

E. means forming a fourth side of said quadrilateral, said fourth sidebeing disposed opposite said second side.

2. An improvement as defined in claim 1, said means forming said thirdside including a further leaf spring flexing in a direction identical tothe springing motion of said air spring means, said clamping yoke beingaffixed approximately to the middle of said further leaf spring, atleast one end of said further leaf spring being connected to saidchassis.

3. An improvement as defined in claim 1, wherein said leaf spring isformed of two spacedly stacked spring leaves.

4. An improvement as defined in claim 1, wherein each end of said axletube is associated with a separate quadrilateral suspension, the leafsprings of the two suspensions are interconnected by a transversal beamsupporting said chassis through said air spring means.

5. An improvement as defined in claim 4, wherein said beam is hollow andlongitudinally open.

6. An improvement as defined in claim 4, wherein said beam is anon-bendable torsion bar.

7. An improvement as defined in claim 4, including A. a linkage bracketattached to said chassis, said linkage bracket forming said fourth side,

B. a first support member securing one end of said leaf spring to saidlinkage bracket,

C. a second support member securing the other end of said leaf spring tosaid transversal beam and D. a third support member securing the midportion of said leaf spring to said clamping yoke.

8. An improvement as defined in claim 7, wherein said second supportmember rigidly secures said leaf spring and said transversal beam to oneanother.

1. In an axle suspension for automotive vehicles of the type including (a) a vehicle chassis, (b) a differential associated with the axle, (c) a drive shaft for driving said axle, (d) an axle bracket pivotally connected to the vehicle chassis, (e) a horizontal axle tube affixed to said axle bracket and extending substantially normal to the direction of travel and (f) air spring means supported at least indirectly by said axle bracket and connected to said chassis, the improvement comprising a quadrilateral suspension having A. a leaf spring constituting said axle bracket and forming a first side of said quadrilateral suspension, said leaf spring being relatively wide in a first plane extending substantially vertically and longitudinally relative to the direction of travel, said leaf spring being relatively narrow in a second plane normal to said first plane, said leaf spring being adapted to flex in a direction parallel with said axle tube, B. a clamping yoke forming a second side of said quadrilateral suspension and situated adjacent said leaf spring, said clamping yoke carrying said axle tube and C. means for jointedly securing said clamping yoke to said leaf spring, D. means forming a third side of said quadrilateral suspension, said third side being disposed opposite said first side, and E. means forming a fourth side of said quadrilateral, said fourth side being disposed opposite said second side.
 2. An improvement as defined in claim 1, said means forming said third side including a further leaf spring flexing in a direction identical to the springing motion of said air spring means, said clamping yoke being affixed approximately to the middle of said further leaf spring, at least one end of said further leaf spring being connected to said chassis.
 3. An improvement as defined in claim 1, wherein said leaf spring is formed of two spacedly stacked spring leaves.
 4. An improvement as defined in claim 1, wherein each end of said axle tube is associated with a separate quadrilateral suspension, the leaf springs of the two suspensions are interconnected by a transversal beam supporting said chassis through said air spring means.
 5. An improvement as defined in claim 4, wherein said beam is hollow and longitudinally open.
 6. An improvement as defined in claim 4, wherein said beam is a non-bendable torsion bar.
 7. An improvement as defined in claim 4, including A. a linkage bracket attached to said chassis, said linkage bracket forming said fourth side, B. a first support member securing one end of said leaf spring to said linkage bracket, C. a second support member securing the other end of said leaf spring to said transversal beam and D. a third support member securing the mid portion of said leaf spring to said clamping yoke.
 8. An improvement as defined in claim 7, wherein said second support member rigidly secures said leaf spring and said transversal beam to one another. 